Fig. 4. Principal component analysis (PCA) of community-level physiological profiles (CLPP) obtained for microbial communities from fallow soil and rhizosphere microbial communities of canola varieties grown at Watson, Saskatchewan, sampled in May, June, July, August, and October 1999 and April 2000. Closed circles represent fallow soil (n = 4). Closed triangles represent conventional variety, Excel (n = 4). Open squares represent genetically modified variety, Quest (n = 4). Error bars represent the standard error of the mean. Percent variation explained by each PC is marked in parentheses. P values have been included when a significant variety effect is present, as determined by analysis of variance (ANOVA). Reproduced with permission from Dunfield and Germida (2003).